Rotational movement damper

Abstract

The invention relates to a rotational movement damper ( 1 ) comprising an outer sleeve ( 2 ) and an axle which fits in the outer sleeve ( 2 ) and mounted to rotate in the outer sleeve. The axle comprises at least two discoidal flanges ( 7, 8, 17, 18 ) with flat flange surfaces ( 9, 10 ) and the same diameter, fitting in annular channels ( 12, 13, 14, 15 ) in the outer sleeve ( 2 ) such that the flanges contact with the planar flange surfaces ( 9, 10 ) thereof against the equally planar area on the counter surfaces of the annular channels ( 12, 13, 14, 15 ) unaffected by temperature variations and, on counter-rotation of the outer sleeve ( 2 ) and axle ( 3 ) act as a slipper clutch.

The invention claimed is: 
     
       1. A rotational movement damper comprising:
 an outer sleeve having an axial hole and at least two identical annular channels extending radially outward from the axial hole, each of the identical annular channels having flat upper and lower counter surfaces; and 
 an axle having at least two identical discoidal flanges with flat upper and lower flange surfaces which fit into the outer sleeve and is mounted to rotate in the outer sleeve, 
 wherein the identical discoidal flanges of the axle and the identical annular channels have outer diameters that are equal, and the flat upper and lower flange surfaces of the identical discoidal flanges and the flat upper and lower counter surfaces of the identical annular channels have planar areas that are equal, 
 so that when the axle and the outer sleeve are mounted together, the axle is firmly engaged by the outer sleeve, in a way that the flat upper and lower flange surfaces of each of the identical discoidal flanges face against a corresponding one of the flat upper and lower counter surfaces of the corresponding identical annular channels, and 
 on counter-rotation of the outer sleeve and the axle, the rotational movement damper acts as a slipper clutch, in which friction between the outer sleeve and the axle during mutual rotation is overcome when a torque on the rotational movement damper exceeds a predetermined amount, and 
 wherein at least one of the outer sleeve and the axle of the rotational movement damper is formed of plastic and the outer sleeve comprises a plurality of teeth evenly spaced on an outer circumference of the outer sleeve. 
 
     
     
       2. The rotational movement damper according to  claim 1 , wherein each of the identical discoidal flanges is formed with a rounded head surface around an outer circumference thereof. 
     
     
       3. The rotational movement damper according to  claim 2 , wherein when a vertical cross-section of the discoidal flanges is viewed, the rounded head surface of each of the identical discoidal flanges has a semi-circular shape which extends between the flat upper and lower flange surfaces. 
     
     
       4. The rotational movement damper according to  claim 2 , wherein the identical discoidal flanges have shapes that are a converse of shapes of the identical annular channels, so that a bottom surface and the counter surfaces of the identical annular channels fit against the head surface and the flat upper and lower flange surfaces of the axle. 
     
     
       5. The rotational movement damper according to  claim 1 , wherein each of the identical discoidal flanges is formed with a cylinder-shaped circumference. 
     
     
       6. The rotational movement damper according to  claim 5 , wherein when a vertical cross-section of the identical discoidal flanges is viewed, the cylinder-shaped circumference of each of the identical discoidal flanges has a linear shape which extends between the flat upper and lower flange surfaces. 
     
     
       7. The rotational movement damper according to  claim 5 , wherein the identical discoidal flanges have shapes that are a converse of shapes of the identical annular channels, so that a bottom surface and the counter surfaces of the identical annular channels fit respectively against the cylinder-shaped circumference and the flat upper and lower flange surfaces of the axle. 
     
     
       8. The rotational movement damper according to  claim 1 , wherein the axle is configured so that when the outer sleeve is mounted on the axle a gap exists between the outer sleeve and a ring flange of the axle. 
     
     
       9. The rotational movement damper according to  claim 1 , since at least one of the outer sleeve and the axle of the rotational movement damper is formed of the plastic, a frictional force between the axle and the outer sleeve is able to remain substantially constant during an expansion or a contraction of the outer sleeve and the axle caused by a temperature change. 
     
     
       10. The rotational movement damper according to  claim 1 , wherein the teeth are arranged in a linear direction along a portion of an outer circumference of the outer sleeve,
 wherein each of the teeth arranged in the linear direction on one lateral side of the outer sleeve is directly opposite another one of the teeth on an opposite lateral side of the outer sleeve. 
 
     
     
       11. The rotational movement damper according to  claim 1 , wherein a portion of the outer sleeve below the teeth has a uniform circular outer surface. 
     
     
       12. A rotational movement damper, comprising:
 an outer sleeve having an axial hole and at least two annular channels extending radially outward from the axial hole, each of the annular channels having flat upper and lower counter surfaces; and 
 an axle having at least two discoidal flanges with flat upper and lower flange surfaces which fits into the outer sleeve and is mounted to rotate in the outer sleeve, 
 wherein the discoidal flanges of the axle and the annular channels have diameters that are equal, and the flat flange surfaces of the discoidal flanges and the counter surfaces of the annular channels have planar areas that are equal, 
 wherein when the axle is fitted into the outer sleeve, the flat flange surfaces of each of the discoidal flanges face against the flat counter surfaces of the corresponding annular channels, and 
 on counter-rotation of the outer sleeve and the axle, the rotational movement damper acts as a slipper clutch, in which friction between the outer sleeve and the axle during mutual rotation is overcome when a torque on the rotational movement damper exceeds a predetermined amount, and 
 wherein at least one of the outer sleeve and the axle of the rotational movement damper is formed of plastic, 
 wherein the axle includes: 
 a stub on one end thereof which projects from one end of the outer sleeve, and 
 a ring flange and a hex-bolt head on an opposite end thereof which projects from an opposite end of the outer sleeve. 
 
     
     
       13. The rotational movement damper according to  claim 12 , wherein the ring flange has a diameter larger than each of the diameters of the discoidal flanges of the axle and an outer diameter of the outer sleeve. 
     
     
       14. A method of making a rotational movement damper, comprising:
 forming an outer sleeve with an axial hole and at least two identical annular channels extending radially outward from the axial hole, each of the identical annular channels having flat upper and lower counter surfaces; and 
 forming an axle with at least two identical discoidal flanges with flat upper and lower flange surfaces which are adapted to be fit into the outer sleeve and to be mounted to rotate in the outer sleeve, 
 wherein the identical discoidal flanges of the axle and the identical annular channels have outer diameters that are equal, and the flat upper and lower flange surfaces of the identical discoidal flanges, and the flat upper and lower counter surfaces of the identical annular channels have planar areas that are equal, 
 so that when the axle and the outer sleeve are mounted together, the axle is firmly engaged with the outer sleeve, in a way that the flat upper and lower flange surfaces of each of the identical discoidal flanges face against a corresponding one of the flat upper and lower counter surfaces of the corresponding identical annular channels, and 
 on counter-rotation of the outer sleeve and the axle, the rotational movement damper acts as a slipper clutch, in which friction between the outer sleeve and the axle during mutual rotation is overcome when a torque on the rotational movement damper exceeds a predetermined amount, 
 wherein at least one of the outer sleeve and the axle is formed of plastic, and 
 since at least one of the outer sleeve and the axle of the rotational movement damper is formed of plastic, a friction force between the axle and the outer sleeve is able to remain substantially constant during an expansion or a contraction of the outer sleeve and the axle caused by a temperature change, 
 wherein teeth are arranged in a linear direction along a portion of an outer circumference of the outer sleeve, and each of the teeth is directly opposite of the teeth of an opposite side of the outer sleeve. 
 
     
     
       15. The method of making the rotational movement damper according to  claim 14 , the method comprising:
 slanting an uppermost portion of the outer sleeve inwardly from a lower edge thereof, and 
 forming an outer diameter of a lowermost part of the outer sleeve to be greater than inner diameters of the identical annular channels of the outer sleeve. 
 
     
     
       16. The method of making the rotational movement damper according to  claim 14 , the method comprising:
 mounting one of the outer sleeve and the axle onto the other of the outer sleeve and the axle by injection molding so that when the outer sleeve is mounted on the axle, a gap exists between the outer sleeve and a ring flange of the axle. 
 
     
     
       17. The method of making the rotational movement damper according to  claim 14 , the method comprising:
 forming the outer sleeve with a plurality of teeth, 
 the teeth being arranged in a linear direction along a portion of an outer circumference of the outer sleeve, 
 wherein each of the teeth arranged in the linear direction on one lateral side of the outer sleeve is directly opposite another one of the teeth on an opposite lateral side of the outer sleeve. 
 
     
     
       18. The method of making the rotational movement damper according to  claim 14 , the method comprising:
 forming a portion of the outer sleeve with teeth, and 
 forming another portion of the outer sleeve below the teeth with a uniform circular outer surface.